Mitsubishi Electric MELSEC FX2N-2LC, User Manual

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FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7
7-10
7.2.18 BFM #34 (CH1) and BFM #53 (CH2): Integral time (I)
In BFM #34, set the integral time of CH1. In BFM #53, set the integral time of CH2.
The integral operation changes the operation quantity in proportion to the area enclosed by the
deviation size and the period of time in which deviation is generated.
In the proportional operation, even while the operation quantity is stable, deviation (which is the
difference between the set value (SV) and the measured value (PV)) may be caused by natural
radiation, etc. The integral operation eliminates such a deviation. At this time, the period of
time required to obtain, only by the integral operation, the operation quantity equivalent to that
obtained by the proportional operation is called the integral time.
As the integral time is shorter, the integral efficiency is better.
The allowable set range is from 0 to 3,600 sec.
7.2.19 BFM #35 (CH1) and BFM #54 (CH2): Derivative time (D)
In BFM #35, set the derivative time of CH1. In BFM #54, set the derivative time of CH2.
The derivative operation changes the operation quantity in proportion to the measured value
change speed so that increase of deviation (which is the difference between the set value (SV)
and the measured value (PV)) can be prevented from happening.
Because the derivative operation responds to the measured value change ratio, the response
to disturbances (turbulence in the measured value caused by external factors) is improved.
When the deviation increases or decreases at a constant ratio, the period of time required to
obtain, only by the derivative operation, the operation quantity equivalent to that obtained by
the proportional operation is called the derivative time.
As the derivative time is longer, the derivative effect is larger.
The allowable set range is from 0 to 3,600 sec.
When BFM #35/#54 is set to "0", the derivative function is disabled.